Single-use syringe

ABSTRACT

A syringe includes a barrel having a fluid chamber, a proximal end, a distal end and an elongated tip extending from the distal end and having a passageway therethrough in fluid communication with the chamber. A plunger is provided for drawing fluid into and out of the barrel. The plunger includes an elongated plunger rod having a proximal portion and a distal portion connected by a breakable connection. The breakable connection is strong enough to hold the proximal portion and distal portion together during normal use of the syringe and breakable upon application of additional force to the proximal portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 09/274,117 filed on Mar. 23, 1999 which is acontinuation-in-part of U.S. patent application Ser. No. 09/249,431filed on Feb. 12, 1999 which is a continuation-in-part of U.S. patentapplication Ser. No. 09/124,447 filed on Jul. 29, 1998.

FIELD OF THE INVENTION

The present invention relates to a syringe having a breakable plungerrod to prevent further use of the syringe after fluid delivery orinjection. The present invention also relates to fluid transfer deviceshaving improved needle attaching features and in particular, structureto help prevent the removal of a hypodermic needle assembly from a fluidtransfer device such as a hypodermic syringe.

BACKGROUND

Throughout the world the re-use of hypodermic syringe products which areintended for single-use only is instrumental in drug abuse and in thetransfer of contagious diseases. Intravenous drug users who routinelyshare and re-use syringes are a high-risk group with respect to the AIDSvirus. Also, the effects of multiple use are a major concern in somecountries where the repeated use of syringe products during massinoculation programs may be responsible for the spread of many diseases.Syringes are often recycled in developing countries without propersterilization.

Many attempts have been made to remedy this problem. Some designsinvolve the inclusion of structure which will allow the destruction ordefeating of the syringe function through a conscious act by the user,such as breaking a syringe or one of its components. In addition, thereare single-use hypodermic syringes which become incapable of further useautomatically upon delivery of the medication without any additional acton the part of the user. Such syringes are taught in U.S. Pat. No.4,961,728.

With single-use syringes using needle assemblies having a hub attachedto a needle cannula there is a need to prevent the removal of the needleassembly after the use of the single-use syringe so that the needleassembly cannot be used again with other syringes. In addition topreventing the removal of the needle assembly, there is also a need forstructure which will allow the easy attachment of the needle assembly tothe syringe so that the needle assembly may be attached at the time ofuse and an appropriately sized needle may be used.

SUMMARY OF THE INVENTION

A fluid transfer device comprises a barrel having a fluid chamber, aproximal end, a distal end and an elongated tip extending from thedistal end having a passageway therethrough in fluid communication withthe chamber. A collar surrounds the tip. For the purposes of the presentinvention collar is intended to include not only continuous structuresbut also discontinuous structures such as a wall with gaps in itsstructure. At least one deflectable locking tab projects radiallyinwardly from the collar and is adapted to engage the hub of a needleassembly to prevent the removal of the needle assembly away from thetip. The locking tab is configured to allow assembly of the needleassembly to the barrel through axial motion of the hub toward thebarrel.

Another embodiment of the present fluid transfer device includes aneedle assembly having a cannula with a proximal end, a distal end, anda lumen therethrough. A hub includes an open proximal end with a cavitytherein and a distal end is joined to the proximal end of the cannula sothat the lumen is in fluid communication with the cavity. The hubincludes an outside surface. A barrel having a fluid chamber includes anopen proximal end, a distal end and an elongated frusto-conically shapedtip extending from the distal end having a passageway therethrough influid communication with the chamber. A collar surrounding the tipincludes a plurality of deflectable locking tabs projecting radially andproximally inwardly from the collar defining an inner aperturesurrounding the tip. The tip extends distally beyond the aperturedefined by the locking tabs. The needle assembly is connected to thebarrel so that the elongated tip of the barrel is in the cavity of thehub and the outside surface of the hub is adjacent to the inner aperturedefined by the locking tabs so that the locking tabs prevent removal ofthe needle assembly from the barrel through contact between the lockingtabs and the outside surface of the hub.

Another embodiment of the present fluid transfer device includes meanson the hub between the distal end of the hub and the proximal end of thehub for allowing the hub to break upon application of a bending force tothe hub. Such means includes a fracturable section between the proximalend and the distal end of the hub such as an annular discontinuity onthe outside surface of the hub or an annular discontinuity in the cavityof the hub. The fracturable section is provided to prevent removal ofthe needle assembly from the fluid transfer device by allowing the hubto break if an excessive bending force is applied to the hub.

Another embodiment of the present invention includes a plunger having anelongated plunger rod, a proximal portion and a distal portion. Thedistal portion includes a stopper slidably positioned in fluid-tightengagement with an inside surface of the barrel for drawing fluid intoand out of the barrel by movement of the plunger relative to the barrel.The plunger further includes means for allowing the connection betweenthe proximal portion of the plunger rod and the distal portion of theplunger rod to break upon application of additional force to theproximal portion. The means for allowing the connection between theproximal portion of the plunger and the distal portion to break caninclude an axial projection on one of the proximal portion and thedistal portion having at least one transverse protuberance projectingtherefrom. The protuberance is connected to the other of the proximalportion and the distal portion and the breakable connection is on theprotuberance. Preferably, there are a plurality of protuberances andmore preferably, there are four protuberances with two protuberancesprojecting from one side of the axial projection and two protuberancesprojecting from another side of the axial projection, preferably insubstantially opposite directions.

Another embodiment of the present invention includes a plunger having adistally directed extension on the distal portion of the plunger rodshaped to fit within the passageway of the tip of the syringe barrelwhen the plunger is positioned distally with respect to the barrel. Thepurpose of the distally directed extension is to drive as muchmedication out of the syringe barrel as possible and therefore reducewasted medication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fluid transfer device of the presentinvention with a needle assembly attached;

FIG. 2 is an exploded prospective view of the fluid transfer device andneedle assembly of FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the fluid transfer deviceof FIG. 2 taken along line 3—3;

FIG. 4 is a side-elevational view of the left side of the fluid transferdevice of FIG. 2;

FIG. 5 is an enlarged partial cross-sectional view of the needleassembly and fluid transfer device of FIG. 1 taken along line 5—5;

FIG. 6 is a perspective view of the needle assembly of FIG. 2;

FIG. 7 is an alternative needle assembly, similar to the needle assemblyof FIG. 6;

FIG. 8 is an enlarged partial cross-sectional view of an alternativefluid transfer device of the present invention;

FIG. 9 is an enlarged cross-sectional view of another alternativeembodiment of the present invention;

FIG. 10 is an enlarged side-elevational view of an alternativeembodiment of the present invention including a flexible tube;

FIG. 11 is an enlarged cross-sectional view of the fluid transfer deviceof FIG. 10 taken along line 11—11;

FIG. 12 is an enlarged cross-sectional view illustrating the barrel ofthe fluid transfer device of FIG. 2 during the manufacturing process;

FIG. 13 is a side elevational view of an alternative embodiment of thefluid transfer device of the present invention;

FIG. 14 is an enlarged cross-sectional view of the fluid transfer deviceof FIG. 13 taken along line 14—14;

FIG. 15 is a side-elevational view of the fluid transfer device of FIG.13 illustrating the hub breaking upon application of a bending force;

FIG. 16 is an enlarged cross-sectional view of another alternative fluidtransfer device;

FIG. 17 is a perspective view of the plunger of an alternativeembodiment of the present invention having a distal portion and aproximal portion connected by a breakable connection;

FIG. 18 is a side elevation view of a syringe assembly using the plungerof FIG. 17;

FIG. 19 is a side elevational view of the syringe of FIG. 18 illustratedwith a force being applied to break the connection to the proximal anddistal ends of the plunger rod;

FIG. 20 is a side elevational view of the syringe of FIG. 19illustrating the separated proximal and distal ends of the plunger rod;

FIG. 21 is a perspective view of the plunger of an alternativeembodiment of the present invention;

FIG. 22 is an enlarged partial cross-sectional view of the plunger ofFIG. 21 taken along lines 22—22;

FIG. 23 is a partially cross-sectional side elevational view of asyringe assembly using the plunger of FIG. 21;

FIG. 24 is a partially cross-sectional side elevational view of analternative syringe assembly embodiment of the present invention havinga cannula attached directly to the syringe barrel.

FIG. 25 is a perspective view of an alternative embodiment of theplunger of the present invention;

FIG. 26 is a partially cross-sectional side elevational view of analternative embodiment of the present invention; and

FIG. 27 is an enlarged partially cross-sectional view of an alternativeplunger of the present invention.

DETAILED DESCRIPTION

While this invention is satisfied by embodiments in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as exemplary of theprinciples of the invention and is not intended to limit the inventionto the embodiments illustrated. The scope of the invention will bemeasured by the appended claims and their equivalents.

Adverting to FIGS. 1-7 a fluid transfer device such as syringe 20includes a barrel 21 having a barrel inside surface 22, a fluid chamber23, a proximal end 25, a distal end 27 and an elongated tip 28 extendingfrom the distal end having a passageway 29 therethrough in fluidcommunication with the chamber. In this embodiment the elongated tip ispreferably frusto-conically shaped.

Barrel 21 further includes a collar 31 having an inside surface 32 andat least one deflectable locking tab projecting radially inwardly fromthe collar. The collar preferably but not necessarily surrounds the tip.In this preferred embodiment, there are a plurality of locking tabs 34projecting radially and proximally inwardly from the inside surface. Inthis preferred embodiment a distal end 30 of elongated tip 28 extendsdistally beyond distal end 33 of the collar. It is preferable that thecollar and the locking tabs are integrally formed of a single materialpreferably a metal such as stainless steel or a plastic material such aspolypropylene. Also, the collar can be made of thermoplastic materialand the locking tabs of metal, such as stainless steel attached to thecollar.

The fluid transfer device of the present invention is intended to beused with a needle assembly 40 including a cannula 41 having a proximalend 43 a distal end 44 and a lumen 45 therethrough. The needle assemblyalso includes a hub 47 having an open proximal end 49 with a cavity 50therein, and a distal end 51 joined to proximal end 43 of cannula 41 sothat lumen 45 is in fluid communication with cavity 50. Hub 47 alsoincludes outside surface 52. The hub in this embodiment preferably, butnot necessarily, includes at least one projection extending radiallyoutwardly from outside surface 52 of the hub. This embodiment includestwo projections 53. It is within the purview of the present invention toinclude needle assemblies having one-piece construction wherein thecannula and the hub are formed of one piece.

Some prior art syringe barrels include a collar around the distal tiphaving a thread on the inside surface of the collar. This configurationis often referred to as a locking luer collar. A needle assembly havinga hub with outwardly extending projections is placed on the distal endof the syringe by aligning the distal tip of the syringe with a cavityin the hub and moving the needle assembly toward the syringe so that theoutward projections of the hub engage the thread. The needle assembly isthen rotated or screwed into the locking luer collar so that the needleassembly is held tightly on the distal tip of the syringe barrel throughinteraction of the locking luer collar thread and the projections on thehub. This is an excellent structure for most applications since itallows for applying the appropriate sized needle assembly at the time ofuse and for changing needle assemblies during a procedure which mayrequire two or more different sizes. However, for many applications itis not desirable to have structure which provides for the easy removalof the needle assembly. For example, in mass inoculation programs usingsingle-use syringes, a needle assembly which is not removablecompliments the syringe assembly which is not reusable. Although mosthealthcare institutions have procedures for disposal of used fluidtransfer devices, an unscrupulous healthcare worker can, if thestructure allows, remove the relatively small hypodermic needle assemblybefore disposing of the larger syringe assembly catheter or I.V. set.

The present invention provides structure to prevent removal of theneedle assembly during normal use of the fluid transfer device. Inparticular, the locking tab projecting radially inwardly from the insidesurface of the collar is adapted to engage the outside surface of thehub of the needle assembly to prevent removal of the needle assemblyaway from the tip of the barrel. The locking tab is configured to allowassembly of needle assembly to the syringe barrel through axial motionof the hub toward the barrel. In use, the needle assembly is connectedto the barrel by moving the needle assembly toward the barrel so thatelongated tip 28 of the barrel is in cavity 50 of the hub and outsidesurface 52 of the hub is adjacent to locking tabs 34 so that the lockingtab prevents removal of the needle assembly from the barrel throughcontact of the locking tabs with the outside surface of the hub.Accordingly, the force for removal of the needle assembly from thesyringe is much higher than the force for installation of the needleassembly to the barrel. This is an important feature of the presentinvention.

Although only one locking tab is required for the present invention, thepreferred embodiment illustrated herein includes a plurality of lockingtabs 34 which are deflected by the proximal end and/or the outsidesurface of the hub when the needle assembly is installed onto thebarrel. Tabs 34 are separated by gaps 35 to allow them to flex morefreely and provide for lower forces when attaching the needle assemblyto the barrel. The locking tabs include distal ends 37 which in thispreferred embodiment describe a opening 39 which is preferablycircularly shaped and smaller than the outside surface of the hub and/orthe width described by projections 53 so that the locking tabs deflectwhen the needle assembly is installed onto the barrel. Because thelocking tabs are facing radially and proximally inwardly after needleattachment they are very resistant to flexing outwardly to allow theremoval of the needle assembly, as best illustrated in FIG. 5. Someportion of the outside surface of the hub preferably describes adimension which is larger than the opening 39 described by the distalends 37 of the locking tabs so that an attempt to remove the needleassembly there will not be enough space for the tabs to move towards aposition which is perpendicular to the longitudinal axis of the barrel.

In this preferred embodiment, the needle assembly includes projections53 projecting outwardly from the outside surface of the hub to helpprevent removal of the needle assembly from the barrel through contactbetween the locking tabs and the projections. The present invention canaccomplish its purpose without the radial projection or projections onthe hub however the projection or projections provide a strongerattachment of the needle assembly to the barrel and allow for moreliberal tolerances for the locking tab dimensions.

An alternate needle assembly 140 is illustrated in FIG. 7. This needleassembly is similar to the needle assembly 40 and includes cannula 141and hub 147. Hub 147 includes one projection 153 extending 360° aroundthe hub. This structure is especially desirable if only one or twolocking tabs are used so that it is not necessary to align theprojection on the needle hub with the locking tabs since the projectionon the hub will always be positioned so that it can contact a lockingtab.

The syringe of the present embodiment further comprises a plunger 59including a plunger rod 61 having an elongated body portion 62 having aproximal end 63, a distal end 64 and a stopper 65 at the distal end. Thestopper is slidably positioned in fluid-tight engagement with the barrelinside surface. The plunger rod extends outwardly from proximal end 25of the barrel. The plunger rod is accessible outside of proximal end 25of the barrel and is provided to move the stopper along the barrel toforce fluid into and out of chamber 23 through passageway 29.Disc-shaped plunger rod flange 67 is provided as a convenient structurefor applying forces to move the plunger rod with respect to barrel 21. Aflange 26 is also provided at the proximal end of the barrel tofacilitate handling and for maintaining the relative position of thebarrel with respect to the plunger rod during fluid transfer using knownprocedures.

It is within the purview of the present invention to include plungerrods and stoppers which are separately formed or integrally formed ofthe same material or different materials such as in two-color molding,or separately formed of the same or different materials and joinedtogether by mechanical means, adhesives, ultrasonic welding, heatsealing or other suitable means. It is understood that the plunger ofthe present embodiment merely illustrates these many possibilities.

FIG. 8 illustrates an alternative embodiment of the present invention.This embodiment is structurally and functionally similar to theembodiment of FIGS. 1-7. In this embodiment, barrel 121 having a chamber123, a distal end 127 and an elongated frusto-conically shaped tip 128extending from the distal end and having a passageway 129 in fluidcommunication with the chamber. A collar 131 preferably surrounds thetip. A plurality of deflectable locking tabs 134 project radially andproximally inward from the collar and toward the tip. Distal ends 137 ofthe locking tabs define an opening for allowing attachment of a needleassembly to the barrel. In this embodiment, distal end 130 of tip 128does not extend beyond distal end 133 of the collar as it does in thepreferred embodiment of FIGS. 1-7. Having the distal end of the tipextend beyond the distal end of the collar is preferred because it iseasier to see the tip of the barrel and to align the barrel tip with thehub cavity for attachment of the needle assembly to the barrel. However,this structure is preferred and not necessary to carry out the presentinvention. A shorter tip may be desired for various reasons includingreducing the amount of material in the barrel.

FIG. 9 illustrates another alternative embodiment of the presentinvention. This embodiment is similar to the embodiment of FIGS. 1-7. Inthis alternative embodiment, barrel 221 includes an elongated tip 228extending from distal end 227 of the barrel and having a passageway 229therethrough in fluid communication with a chamber 223. A collar 231surrounds the tip. A mounting element 224 is attached to the collar. Themounting element includes at least one locking tab, and in thisembodiment, a plurality of locking tabs 234. In this embodiment it ispreferred that mounting element 224 and locking tabs 234 are integrallyformed of the same material selected form the group of plastic and metalwith stainless steel being preferred. The mounting element allows formolding the barrel with a straight collar after which the mountingelement can be attached to the distal end of the collar. In thisembodiment, deflectable locking tabs are projecting radially inwardly.They are configured so that when the needle assembly is attached to thebarrel the hub will force the locking tabs to project radially inwardlyand proximally inwardly in an orientation similar to the locking tabs ofFIGS. 3 and 8 to prevent the removal of the needle assembly away fromthe tip after attachment. In this embodiment the locking tabs can alsobe positioned to project radially inwardly and proximally before theinstallation of the needle assembly as with the locking tabs of FIGS. 3and 8. The mounting element can be attached to the collar throughvarious means such as adhesive, welding and/or mechanical means such aspress fitting or having locking tabs in the mounting element which allowit to be pressed onto the collar but not removed.

FIGS. 10 and 11 illustrate another alternative embodiment of the presentinvention. This embodiment is illustrated with needle assembly 40 whichis identical to the needle assembly of FIG. 6. In this embodiment, fluidtransfer device 320 includes a barrel 321 having a chamber 323 and anelongated tip 328 extending from distal end 327 of the barrel and havinga passageway 329 therethough in fluid communication with the chamber. Acollar 331 preferably surrounds the tip and includes a plurality ofdeflectable locking tabs 334 projecting radially and proximally inwardlyfrom said collar. A flexible tube 370 having a proximal end, a distalend 371 and a bore 373 therethrough. The distal end of flexible tube 370is connected to barrel 321 so that bore 373 is in fluid communicationwith said passageway. Tube 370 can be a catheter or it can be part of anI.V. fluid administration set or various other fluid transfer devices.

One method of manufacturing barrel 21 of the present invention is toinjection mold the barrel out of thermoplastic material so thatdeflectable locking tabs 34 are projecting radially and distallyinwardly from collar 31 as illustrated in FIG. 12. This configurationallows for easy removal of the barrel from the injection mold. Aftermolding, locking tabs 34 are bent inwardly using force or heat or acombination thereof so that the locking tabs assume a radially andproximally inwardly directed orientation as illustrated in FIG. 3.

FIGS. 13-15 illustrate another alternative embodiment of the fluidtransfer device of the present invention. This embodiment is similar tothe embodiment of FIGS. 1-7. In this embodiment, fluid transfer device420 includes a barrel 421 having an elongated tip 428 extending fromdistal end 427 of the barrel and having a passageway 429 therethrough. Acollar 431 preferably surrounds the tip and includes a plurality ofdeflectable locking tabs 434 projecting radially and proximally inwardlyfrom the collar.

A needle assembly 440 includes a cannula 441 having a proximal end 443,a distal end 444 and a lumen therethrough. The needle assembly alsoincludes a hub 447 having an open proximal end 449 with a cavity 450therein, and a distal end 451 joined to the proximal end 443 of thecannula so that the lumen is in fluid communication with the cavity. Hub447 also includes outside surface 452. The hub in this embodimentpreferably, but not necessarily, includes projections 453 extendingradially outwardly from the outside surface of the hub.

A needle shield 480 includes an open proximal end 481, a distal end 482and a side wall 483 therebetween defining a cavity 484 in the shield.The cavity includes inside surface 485. The shield is removablyconnected to hub 447 so that distal end 444 of the cannula is containedwithin cavity 484 of the shield. The removable connection between theshield and the hub is preferably achieved by frictional engagementbetween inside surface 485 of the shield and outside surface 452 of thehub. There are numerous ways for removably connecting a shield to a hubincluding a snap-fit arrangement or threaded engagement with thefrictional engagement described herein being merely representative ofthese many possibilities, all of which are within the purview of thepresent invention. The needle shield is provided to protect the cannulafrom damage or contamination.

In this embodiment, hub 447 further includes means on the hub betweenthe distal end and the proximal end of the hub for allowing the hub tobreak upon application of bending force to the hub. In this embodiment,the means for allowing the hub to break includes a fracturable sectionin the form of annular discontinuity 454 on outside surface 452 of thehub which creates a fracturable section which will cause the hub tobreak upon application of force F illustrated in FIG. 15. As indicatedhereinabove, the fluid transfer device of the present invention providesstructure to prevent removal of the needle assembly in the form of oneor more locking tabs projecting radially inwardly from the insidesurface of the collar which are adapted to engage the outside surface ofthe hub of the needle assembly. This structure is provided to preventthe improper and undesirable removal of the needle assembly from thebarrel. However, an unscrupulous healthcare worker may attempt to applyexcessive force to remove the needle assembly by grasping the needleshield and applying a bending force which is generally perpendicular tothe longitudinal axis of the cannula in an attempt to cause the hub toovercome the resisting force of the deflectable locking tabs. Sincesubstantial force can be applied it is desirable to have a means on thehub for allowing the hub to break upon the application of a force to thehub which is in excess of the hub forces normally encountered during theknown and proper use of the fluid transfer device. In this embodiment, afracturable section is provided in the form of annular discontinuity 454on the outside surface of the hub. When force F, illustrated in FIG. 15is applied the hub will break, preferably in the area of annulardiscontinuity 454. The discontinuity can, as does in this case, producean area of reduced cross section in the hub so that this area is theweakest portion of the hub. The discontinuity can also be in the shapeof a sharp edge or edges which produce a stress concentration when thehub is subject to bending. In this situation, the result may be obtainedwithout reducing the cross-sectional area significantly or at all. Thedesign would rely on the stress concentration to promote breaking justas scoring of a medication tablet will allow the tablet to break in halfalong the score line. In this embodiment, sharp annular edge 455 is alsoprovided to promote a stress concentration in the area where the hub isintended to break. Breaking in the area of the fracturable section willcause the cannula to be safely trapped within the needle shield and theneedle assembly to be rendered non-reusable. Also, the presence of theproximal end of the hub on the fluid transfer device prevents theaddition of a new needle assembly to the device which could allow theundesirable second use of the fluid transfer device. The discontinuitymay be on the outside surface of the hub or in the cavity of the hub.

Also, means for allowing the hub to break can be achieved through theuse of a brittle material in the entire hub or in the desired breakingarea so that bending force will fracture the hub in the area of thebrittle material. This result can be achieved using two-part ormulti-part molding wherein, for example, the proximal end of the hub ismolded of a resilient plastic and the breaking area and the distal endof the hub is molded of a brittle plastic so that the hub will tend tobreak close to the intersection of the two difference plastics where thelargest bending moment on the brittle plastic would be experienced.Since many plastics can be formulated to exhibit a wide variety ofproperties from very ductile to very brittle, the choice of a hubmaterial is quite broad. When using two-part molding, the plasticsshould be chosen for their properties and for their compatibility witheach other at the intersection of the two plastic materials in the hub.Polypropylene, polyethylene, styrene and polycarbonate are preferredplastic materials for the hub. Styrene and polycarbonate can beformulated to be very brittle and/or sensitive to surfacediscontinuities and can be used for the entire hub for the part of thehub where the fracture is desired. All of the above-described materialsand structures are within the purview of the present invention.

It is an important feature of the present embodiment that it providestwo means for preventing the unwanted removal of the needle assemblyfrom the fluid transfer device. The first is the resisting action of thedeflectable locking tab or tabs against the outside surface of the huband the second is the fracturable section of the hub which will causethe hub to break upon the application of excessive force used in anattempt to overcome the action of the deflectable locking tabs.

FIG. 16 illustrates another alternate embodiment of the fluid deliverydevice of the present invention. In this embodiment, needle assembly 540includes a cannula 541 and a hub 547. The hub includes open proximal end549 with a cavity 550 therein and a distal end 551. Needle assembly 540further includes a fracturable section between the proximal end and thedistal end of the hub for allowing the hub to break upon application ofa bending force to the hub. In this embodiment, the fracturable sectionincludes an annular discontinuity 554 in cavity 550. Annulardiscontinuity 554 also preferably includes sharp annular stressconcentrating edge 555 to help promote breakage in the area of thediscontinuity. This embodiment, like the embodiment of FIGS. 13-15provides two-step protection against the undesirable removal of theneedle assembly from the fluid transfer device. The first protection isoffered by the interaction of flexible locking tabs 534 to hold the hubin its position on projection 553. The second protection is thefracturable section for allowing the hub to break upon the applicationof bending forces on the hub in excess of those experienced duringnormal proper use of the fluid transfer device.

FIGS. 17-20 illustrate another alternative embodiment of the presentinvention. In this embodiment the fluid delivery device is syringe 620comprising barrel 621 having a fluid chamber 623, a proximal end 625, adistal end 627 and an elongated tip 628 extending from the distal endand having a passageway 629 therethrough in fluid communication with thechamber. A collar 631 surrounds the tip. At least one deflectablelocking tab projects radially inwardly from the collar. In thisembodiment, there are a preferably a plurality of locking tabs 634.

A needle assembly 640 includes a cannula 641 having a proximal end 643,a distal end 644 and a lumen therethrough. A hub 647 includes an openproximal end 649 with a cavity therein, and a distal end 651 joined tothe proximal end of the cannula so that the lumen is in fluidcommunication with the cavity of the hub. The hub further includes anoutside surface 652. The needle assembly is connected to the barrel sothat the elongated tip of the barrel is in the cavity of the hub and theoutside surface of the hub is adjacent to the one or more locking tabsso that the locking tabs prevent removal of the needle assembly from thebarrel through contact between the locking tab and the outside surfaceof the hub. Locking tabs are configured to allow the assembly of theneedle assembly to the barrel through axial motion of the hub toward thebarrel.

A plunger 659 includes an elongated plunger rod 661 having alongitudinal axis 662, a proximal portion 663 and a distal portion 664connected by a breakable connection 668. Distal portion 664 includes astopper 665 slidably positioned in fluid-tight engagement with an insidesurface 622 of the chamber for drawing fluid in and out of the chamberby movement of the plunger relative to the barrel. Stopper 665 may be aseparate element connected to distal portion 664 or it may be integrallymolded with the distal portion in a one-piece plastic construction.Separate stoppers are preferably made of elastomeric material such asnatural rubber, synthetic rubber, thermoplastic elastomers andcombinations thereof. Breakable connection 668 is strong enough to holdproximal portion 663 and distal portion 664 together during normal useof the syringe and is breakable upon application of additional force tothe proximal portion.

Proximal end 663 further includes a flange 667 for applying forces tomove the plunger rod with respect to the barrel and for breaking thebreakable connection. A flange 626 is also provided at the proximal endof the barrel to facilitate handling of the syringe and for applyingforces to the plunger using a one-handed procedure as will be explainedin more detail hereinafter.

In this embodiment, there are a plurality of breakable connectionsconnecting proximal portion 663 and distal portion 664. Specifically,proximal portion 663 includes a distal projection 669 having at leastone transverse protuberance projecting therefrom. In this preferredembodiment, there are four transverse protuberances 670. Theprotuberances are connected to distal portion 664 and the breakableconnection is on the protuberance. In this preferred embodimentbreakable connection 671 is on the distal end of the protuberance. Thedistal projection may be circularly shaped and fit into a cylindricallyshaped recess in the distal portion. With this structure a singleprotuberance extending up to 360 degrees may be used. The structure mayalso be reversed so that the projection extends proximally from thedistal portion toward the proximal portion.

In this preferred embodiment, proximal portion 663 and distal portion664 and the breakable connections are integrally molded of plasticmaterial. A wide variety of plastic materials are suitable for moldingthe plunger with polystyrene, polypropylene and polyethylene beingpreferred. It is important to control the modulus of elasticity ofmaterial selected for the transverse protuberances which are part of thebreakable connection between the proximal portion and the distal portionof the plunger rod. The breakable connection must break or fail beforethe proximal portion of the plunger bottoms out or makes contact withthe distal portion of the plunger. If the modulus is too high the breakwill occur too easily, causing premature breakage. If the modulus is toolow the breakable connection may not break before the proximal portionand the distal portion contact each other. Also, careful controlling ofthe modulus will allow use of materials such as polypropylene whichwould not normally be used to form a breakable connection. It ispreferred to have a modulus of elasticity be within the range of about800 MPa to 4000 MPa.

The breakable connections can be anywhere along the protuberance, at itsproximal end, its distal end, or in between, depending on, among otherthings, the geometry of the protuberance. A breakable connection canalso be made by connecting the protuberance to the distal end or to theproximal end using a frangible adhesive. The protuberance may be veryshort and made entirely of adhesive or frangible material. Theconnection can also be made using a shear pin passing through the distalprojection 669 and distal portion 664. The shear pin may be made ofplastic with one or more notches or stress risers suitably placed tocause breaking at the desired force levels. The breakable connectionbetween the proximal portion and the distal portion may also beaccomplished by using a snap-fit arrangement a portion of which isdamaged or broken when the desired force is applied. In this lattersituation, the distal portion and the proximal portion can beindividually molded and snapped together during the assembly process.

In use, the syringe of this embodiment can be filled from a vial,ampoule or other suitable container using known safe procedures. Animportant advantage of the present embodiment is that the plunger can bemoved back and forth along the barrel as many times as necessary toproperly fill the syringe barrel. For example, the syringe barrel may befilled with sterile water and then the sterile water can be injectedinto a vial containing a lyophilized medication which is then drawn backinto the syringe barrel. Many single-use syringes in the prior art onlyallow one proximal motion of the plunger with respect to the barrel.With these single-use syringes, once the plunger is moved in a distaldirection with respect to the barrel it can no longer be withdrawn.Therefore, mixing sterile water and a lyophilized medication asdescribed above is not possible.

Another advantage of the present embodiment is that the plunger can bemoved to its distal-most position with respect to the barrel and thenmoved proximally. Some prior art single use syringes automatically lockthe plunger to the barrel when the plunger is moved to its distal-mostposition. These prior art designs can lead to unintentional locking ofthe plunger before use and can compromise filling and mixing procedures.

The liquid in the barrel can now be injected into a patient or deliveredin another suitable manner such as through the pierceable septum of acatheter connector. Upon completion of the injection the user can applyan additional force indicated as A in FIG. 19, to the proximal portion.In this embodiment the breakable connections are broken by theapplication of a distally directed force A applied to the proximal endof the proximal portion along longitudinal axis 662. Force A issufficient to break the breakable connections which causes the plungerrod to separate into two or more unusable pieces. In this enablement theproximal portion and the distal portion are separated as illustrated inFIG. 20.

An important advantage of the present invention is that the breakableconnection can be broken using any one-handed technique, for example,pressing on plunger rod flange 667 in direction A with the thumb of onehand while holding the syringe barrel and/or the syringe barrel flangewith some or all of the remaining fingers. This is desirable over atwo-handed technique wherein the barrel must be held by one hand and theplunger by another to carry out a breaking manipulation such as bendingor twisting.

The embodiment of FIGS. 17-20 is a significant advance over single-usesyringes of the prior art. In particular, it allows multiple strokes ofthe plunger with respect to the barrel without automatically locking andrendering the syringe unusable. This design also allows the plunger tomove to its distal-most position inside the barrel without automaticallylocking the plunger to the barrel. It also provides two mechanisms toprevent or discourage re-use. First, the needle assembly is securelylocked in place so that it cannot be removed from the barrel forimproper re-use. Second, the plunger is breakable so that its proximaland distal ends are separated and the syringe, with the needle locked inplace, can no longer be used to inject medication. Further, the plungerbreaking feature is accomplished by a simple onehanded procedure.

FIGS. 21-23 illustrate another alternative embodiment of the presentinvention. In this embodiment, the fluid delivery device is a syringe720 comprising a barrel 721 having a fluid chamber 723, a proximal end725, a distal end 727 and an elongated tip 728 extending from the distalend and having a passageway 729 therethrough in fluid communication withthe chamber.

A plunger 759 includes an elongated plunger rod 761 having alongitudinal axis 762, a proximal portion 763 and a distal portion 764connected by a breakable connection 768. It is preferred that eitherproximal portion 763 or distal portion 764 include an axial projection.In this embodiment an axial projection 769 is on proximal portion 763.Axial projection 769 includes at least one transverse protuberanceprojecting therefrom. In this preferred embodiment, there are fourtransverse protuberances 770. The protuberances are connected to distalportion 764 and the breakable connection is on the protuberances. Thetransverse protuberances project from opposite sides of the axialprojection. Also, in this embodiment, two of transverse protuberances770 project in substantially the opposite direction than the other twotransverse protuberances 770. It is preferable that proximal portion 763and distal portion 764 and the transverse protuberances 770 whichinclude breakable connections are integrally molded of plastic material.

Plunger 759 in this embodiment functions similarly to plunger 659 in theembodiments of FIGS. 17-20.

Distal portion 764 includes a stopper 765 slidably positioned influid-tight engagement with an inside surface of chamber 723 for drawingfluid into and out of the chamber by movement of plunger 759 relative tobarrel 721. The breakable connection is strong enough to hold theproximal portion and the distal portion together during normal use ofthe syringe and breakable upon application of an additional forceapplied to the proximal portion along the longitudinal axis such asdistally directed force A in FIG. 23. It is preferred that theadditional distally directed force required to break the breakableconnection be within the range of about 2.2 kg to 6.8 kg (5 lbs. to 15lbs.). The proper force depends on various dimensions of the syringebarrel and plunger, the viscosity of the liquid being delivered and themechanical and hydraulic forces encountered by the filling and deliveryprocess. If the breakable connection is too weak the proximal and distalportions will separate during normal use of the syringe and if the forcerequired to break the breakable connection is too high the user may notbe able to easily break the breakable connection as intended. In thisembodiment axial projection 769 is planar shaped having two opposed sidewalls 774 and 775 with at least one transverse protuberance projectingfrom each of the side walls. In this embodiment, there are twotransverse protuberances projecting from each side wall. This structurebecause of the planar axial projection and the diagonal positioning ofthe transverse protuberances is preferred because it creates a securelinkage between the proximal portion and the distal portion and it isstrong with respect to rotational movement or rotational forces appliedto the plunger and weaker with respect to axial forces applied to theplunger so that rotational forces should not break the breakableconnection.

This embodiment further includes distally directed projection 776 on thedistal portion for displacing fluid in passageway 729 when the plungeris positioned distally with respect to the barrel. This is an importantfeature of this embodiment because it saves medication that mightotherwise remain in the passageway after the injection process wascompleted. In an immunization program involving millions of syringes,the amount of medication saved by the cooperative relationship betweenthe distally directed projection and the passageway can be substantial.Even a four percent improvement can result in a free dose for everytwenty-five syringes used.

FIG. 24 illustrates another alternative embodiment of the presentinvention. In this embodiment the fluid delivery device is a syringe 820which functions similarly to the syringe of the embodiment of FIGS.17-20. The syringe includes a barrel 821 having a fluid chamber 823, aproximal end 825,a distal end 827 and an elongated tip 828 extendingfrom the distal end and having a passageway 829 therethrough in fluidcommunication with the chamber. The syringe further includes a cannula841 having a proximal end 843, a distal end 844 and a lumentherethrough. The proximal end of the cannula is joined to elongated tip828 so that the lumen is in fluid communication with passageway 829. Aplunger 859 having an elongated plunger rod 861, a proximal portion 863and a distal portion 864 connected by a breakable connection 868.

Cannula 841 is preferably permanently connected to the barrel so that itis not replaceable or removable during normal use. There are many waysto connect the cannula to a barrel including adhesives, such as epoxy.An advantage of this embodiment is that it can be configured to savemedication from being wasted and, more importantly, when the breakableconnection is broken the plunger is no longer usable and the needlecannot be removed from the syringe to be used again in an undesirablemanner.

FIG. 25 illustrates an alternative plunger 959 including an elongatedplunger rod 961, having a longitudinal axis 962, a proximal portion 963and a distal portion 964 connected by a breakable connection 968. Eitherthe proximal portion or the distal portion includes an axial projection969 having at least one traverse protuberance 970 projecting therefrom.In this embodiment, the axial projection is part of distal portion 964and the protuberance is connected to the proximal portion. The breakableconnection is on the protuberance and in this embodiment it is generallyin the area where the transverse protuberance joins the proximalportion. Although the plunger in the embodiment of FIG. 25 functionssimilarly to the plunger in the embodiment of FIGS. 21-23, the axialprojection in this embodiment is on the distal portion while the axialprojection in the embodiment of FIGS. 21-23 is on the proximal portion.Accordingly, either the proximal portion or the distal portion mayinclude the axial projection having at least one transverseprotuberance. In this embodiment there are four transverseprotuberances, two of which project from one side of the axialprojection and the other two transverse protuberances project from theother side of the axial projection.

FIG. 26 illustrates another alternative embodiment of the presentinvention. In this embodiment the fluid delivery device is a syringe1020 which functions similarly to the syringe of FIGS. 17-20. Thissyringe includes a barrel 1021 and a plunger 1059. The plunger includesa plunger rod 1061 having a longitudinal axis 1062, a proximal portion1063 and a distal portion 1064 connected by a breakable connection. Theproximal portion includes an axial projection 1069 having at least onetransverse protuberance projecting therefrom. In this embodiment thereare four transverse protuberances 1070 connected to the axialprojection. The breakable connection is strong enough to hold theproximal portion and the distal portion together during normal use ofthe syringe and breakable upon application of an additional forceapplied to the proximal portion along the longitudinal axis. Thebreakable connection is on the protuberance. In this embodimenttransverse protuberances 1070 project from the axial projection and theyare inclined at an angle of approximately 45 degrees from longitudinalaxis 1062. This configuration makes the breakable connection strongerand more able to resist an axial force applied to the proximal portionin a proximal direction than when an additional force is applied in adistal direction along the longitudinal axis. It is preferred that theadditional force necessary to break the breakable connection be lowerwhen applied in a distal direction than when applied in a proximaldirection.

Syringe 1020 further includes means for holding proximal portion 1063 ofthe plunger rod in barrel 1021 after the breakable connection has beenbroken. This is an important feature of the present invention becauseafter the breakable connection is broken it is possible for the proximalportion of the plunger rod to fall out of the barrel. It is preferredthat the proximal portion of the plunger stay within the barrel so thatthe used syringe can be disposed of in its entirety. In this embodimentmeans for holding the proximal portion in the barrel includes aninwardly directed projection in the barrel and an outwardly projectionon the proximal portion of the plunger rod. The inwardly directedprojection on the barrel in this embodiment is annular ring 1088 at theproximal end of the barrel and the outward directed projection on theplunger rod comprises projections 1089. The projection on the plungerrod can be a continuous annular ring or one or more individualprojections. Likewise, the inwardly directed projection in the syringebarrel can be an annular ring or one or more radially inwardly directedprojections. The inside diameter described by annular ring 1088 issmaller than the outside diameter described by radial projections 1089so an additional force is required to push the plunger past annular ring1088 during assembly of the syringe. In this embodiment outwardlydirected projection 1089 is saw-toothed or cam-shaped so that the forcerequired to insert the plunger rod into the barrel through theinterference provided by annular ring 1088 is less in the proximaldirection than in the distal direction.

FIG. 27 is another alternative embodiment of the plunger of the presentinvention. In this embodiment plunger 1159 includes elongated plungerrod 1161 having a proximal portion 1163 and a distal portion 1164. Theplunger of this embodiment functions similarly to the plunger of theembodiment of FIGS. 17-20. Proximal portion 1163 of the plunger rodincludes axial projection 1169 at its distal end having at least onetransverse protuberance projecting therefrom. In this embodiment theaxial projection is planar-shaped and has four transverse protuberances1170 projecting from it and connected to the distal portion. In thisembodiment, the transverse protuberances are planar-shaped and alignedsubstantially perpendicular to longitudinal axis 1162 of the plungerrod. A breakable connection is contained on the transverseprotuberances. The breakable connection is strong enough to hold theproximal portion and distal portion together during normal use of thesyringe and breakable upon the application of an additional forceapplied to the proximal portion along the longitudinal axis. Thisconfiguration of the proximal protuberances is desirable because theprotuberances are easier to manufacture when the proximal portion, thedistal portion and the protuberances are injection molded in a one-piecestructure.

What is claimed is:
 1. A syringe comprising: a barrel having a fluidchamber, a proximal end, a distal end and an elongated tip extendingfrom said distal end having a passageway therethrough in fluidcommunication with said chamber; and a plunger including an elongatedplunger rod having a longitudinal axis, a proximal portion and a distalportion connected by a breakable connection, one of said proximalportion and said distal portion including an axial projection having aplurality of transverse protuberances projecting therefrom, saidprotuberances being connected to the other of said proximal portion andsaid distal portion, said breakable connection being on saidprotuberances, said distal portion including a stopper slidablypositioned in fluid-tight engagement with an inside surface of saidchamber for drawing fluid into and out of said chamber by movement ofsaid plunger relative to said barrel, said breakable connection beingstrong enough to hold said proximal portion and said distal portiontogether during normal use of said syringe and breakable uponapplication of an additional force applied to said proximal portionalong said longitudinal axis.
 2. The syringe of claim 1 wherein saidtransverse protuberances project from opposite sides of said axialprojection.
 3. The syringe of claim 2 wherein said axial projectionincludes four transverse protuberances.
 4. The syringe of claim 3wherein two of said transverse protuberances project in substantiallythe opposite direction from the other two of said transverseprotuberances.
 5. The syringe of claim 1 wherein said axial projectionis planar shaped having two opposed side walls and at least onetransverse protuberance projecting from each of said two side walls. 6.The syringe of claim 1 further including a distally directed extensionshaped to fit within said passageway for displacing fluid from saidpassageway said plunger is positioned distally with respect to saidbarrel.
 7. The syringe of claim 1 wherein said proximal portion, saiddistal portion and said breakable connection are integrally molded ofplastic material.
 8. The syringe of claim 7 wherein the plastic materialhas a modulus of elasticity within the range of about 800 MPa to 4000MPa.
 9. The syringe of claim 1 wherein said breakable connection is madeof material selected from the group of polyethylene, polystyrene,polypropylene and adhesives.
 10. The syringe of claim 1 wherein saidstopper and said distal portion are integrally molded of plasticmaterial.
 11. The syringe of claim 1 wherein said additional force is adistally directed within the range of about 2.2 kg to 6.8 kg (5 poundsto 15 pounds).
 12. The syringe of claim 1 further including a needleassembly including a cannula having a proximal end, a distal end and alumen therethrough, a hub having an open proximal end with a cavitytherein, and a distal end joined to said proximal end of said cannula sothat said lumen is in fluid communication with said cavity, said needleassembly being connected to said barrel so that said elongated tip ofsaid barrel is in said cavity of said hub.
 13. The syringe of claim 12wherein said cannula and said hub are integrally molded of plasticmaterial.
 14. The syringe of claim 12 further including a needle shieldhaving an open proximal end, a distal end and a side wall defining acavity, said shield being removably connected to said hub so that saiddistal end of cannula is contained within said cavity.
 15. The syringeof claim 1 further including a cannula having a proximal end, a distalend and a lumen therethrough, said proximal end of said cannula beingjoined to elongated tip so that said lumen is in fluid communicationwith said passageway.
 16. The syringe of claim 1 further including meansfor holding said proximal portion of said plunger in said barrel aftersaid breakable connection is broken including an inwardly directedprojection in said barrel and an outwardly directed projection on saidproximal portion.
 17. A syringe comprising: a barrel having a fluidchamber, a proximal end, a distal end and an elongated tip extendingfrom said distal end having a passageway therethrough in fluidcommunication with said chamber; and a plunger including an elongatedplunger rod having a longitudinal axis, a proximal portion and a distalportion connected by a breakable connection, one of said proximalportion and said distal portion including an axial projection havingfour transverse protuberances projecting therefrom, said protuberancesbeing connected to the other of said proximal portion and said distalportion, said breakable connection being on said protuberances, two ofsaid transverse protuberances projecting in substantially the oppositedirection from the other two of said transverse protuberances, saidproximal portion, said distal portion and said breakable connectionbeing integrally molded of plastic material, said distal portionincluding a stopper slidably positioned in fluid-tight engagement withan inside surface of said chamber for drawing fluid into and out of saidchamber by movement of said plunger relative to said barrel, saidbreakable connection being strong enough to hold said proximal portionand said distal portion together during normal use of said syringe andbreakable upon application of an additional distally directed forceapplied to a proximal end of said proximal portion along saidlongitudinal axis.
 18. The syringe of claim 17 further including adistally directed extension shaped to fit within said passageway fordisplacing fluid from said passageway said plunger is positioneddistally with respect to said barrel.
 19. The syringe of claim 17further including a needle assembly including a cannula having aproximal end, a distal end and a lumen therethrough, a hub having anopen proximal end with a cavity therein and a distal end joined to saidproximal end of said cannula so that said lumen is in fluidcommunication with said cavity, said needle assembly being connected tosaid barrel so that said elongated tip of said barrel is in said cavityof said hub.
 20. The syringe of claim 19 further including a needleshield having an open proximal end, a distal end and a side walldefining a cavity, said shield being removably connected to said hub sothat said distal end of cannula is contained within said cavity.
 21. Thesyringe of claim 17 wherein said additional distally directed force iswithin the range of about 2.2 kg to 6.8 kg (5 pounds to 15 pounds). 22.A plunger for use in a syringe barrel having a fluid chamber, a proximalend, a distal end and an elongated tip extending from the distal endhaving a passageway therethrough in fluid communication with the chambercomprising: an elongated plunger rod having a longitudinal axis, aproximal portion and a distal portion connected by a breakableconnection, one of said proximal portion and said distal portionincluding an axial projection having four transverse protuberancesprojecting therefrom, said protuberances being connected to the other ofsaid proximal portion and said distal portion, said breakable connectionbeing on said protuberances, two of said transverse protuberancesprojecting in substantially the opposite direction from the other two ofsaid transverse protuberances, said proximal portion, said distalportion and said breakable connection being integrally molded of plasticmaterial, said distal portion including a stopper for slidablepositioning in fluid-tight engagement with an inside surface of asyringe barrel chamber for drawing fluid into and out of said chamber bymovement of said plunger relative to said barrel, said breakableconnection being strong enough to hold said proximal portion and saiddistal portion together during normal use of said syringe and breakableupon application of an additional force applied to a proximal end ofsaid proximal portion along said longitudinal axis.
 23. The plunger ofclaim 22 further including a distally directed extension shaped to fitwithin the passageway of an elongated tip of a syringe barrel fordisplacing fluid from said passageway when said plunger is positioneddistally with respect to said barrel.